In the following year we propose to purify several of the folate binding proteins (FBP) we have identified in rat liver. The FBP-CII from rat cytosol has been purified. We will prepare antibody to this protein in order to use the antiserum as an assay for the distribution of this protein in various tissues. Another protein which will be purified and characterized is the FBP from mitochondria. This protein may play a role in mitochondrial function. Standard techniques of protein purification will be employed and the process will be followed by a rapid in-vitro assay for measuring binding of the natural folate ligand.